Antenna-integrated radio with wireless fronthaul

ABSTRACT

A system is disclosed, comprising: a wireless fronthaul access point coupled to a radio mast and in communication with a remote baseband unit, the wireless fronthaul access point further comprising a first millimeter wave wireless interface; and an antenna-integrated radio for providing access to user equipments (UEs), mounted within line of sight on the radio mast with the wireless fronthaul access point, the antenna-integrated radio further comprising: a second millimeter wave wireless interface configured to receive the digital I and Q signaling information from the remote baseband unit wirelessly via the wireless fronthaul access point, wherein the wireless fronthaul access point thereby wirelessly couples the remote baseband unit and the antenna-integrated radio.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation under 35 U.S.C. § 120 of U.S. patentapplication Ser. No. 15/263,365, filed Sep. 12, 2016, and entitled“Antenna-Integrated Radio with Wireless Fronthaul,” which itself is anon-provisional conversion of, and claims the benefit of priority undereither 35 U.S.C. § 119(e) or § 120 of, U.S. Provisional PatentApplication No. 62/217,557, filed Sep. 11, 2015 and entitled“Antenna-Integrated Radio with Wireless Fronthaul,” each of which arehereby incorporated by reference in its entirety for all purposes. Thepresent application also hereby incorporates by reference U.S. Pat. No.8,879,416, “Heterogeneous Mesh Network and a Multi-RAT Node UsedTherein,” filed May 8, 2013, and U.S. patent application Ser. No.14/853,647, “Low-Latency Inter-eNodeB Coordinated Multi-PointTransmission,” filed Sep. 14, 2015, each in their entirety for allpurposes.

BACKGROUND

Currently, antenna-integrated radios exist. These are devices thatintegrate antennas with remote radio heads (RRHs). A remote radio headincludes power amplifiers (PAs), filters, antennas, and a digitalinterface. Radio signals are received at the antenna, translated intodigital format at the integrated RRH, and sent over a CPRI interface toa baseband unit located separate from the antenna-integrated radio.

Also known in the art is multiple-in, multiple out (MIMO). MIMO providesincreased data rates, and uses multiple antennas to do so. For anexample of a remote radio head, see U.S. Pat. App. No. US20110158081,hereby incorporated by reference in its entirety.

A 2×2 MIMO remote radio head typically includes the followingcomponents. A common public radio interface (CPRI) interface may beprovided from a baseband unit, which handles processing of all radiosignals, into a digital board. The digital board may be coupled to asoftware-defined radio (SDR). The software defined radio may provide twotransmit and two receive channels, with the transmit channels beingcoupled to power amplifiers (PAs) and the receive channels being coupledto low-noise amplifiers (LNAs). The channels may then be coupled to oneor more appropriate filters. The filters may be connected to theantennas via connectors.

SUMMARY

In one embodiment, a system is disclosed, comprising: a wirelessfronthaul access point mounted on a radio mast and configured to receivedigital I and Q signaling information from a remote baseband unit for aplurality of radios, the wireless fronthaul access point furthercomprising a first millimeter wave wireless interface; and anantenna-integrated radio for providing access to user equipments (UEs),mounted within line of sight on the radio mast with the wirelessfronthaul access point, the antenna-integrated radio further comprising:a second millimeter wave wireless interface configured to receive thedigital I and Q signaling information from the baseband unit via thewireless fronthaul access point and facing toward the wireless fronthaulaccess point, a software-defined radio (SDR) configured to receive thedigital I and Q signaling information and output a radio signal, a poweramplifier coupled to the SDR and configured to amplify the radio signalfrom the SDR, a radio frequency (RF) filter coupled to the poweramplifier and configured to filter the radio signal from the poweramplifier, and an antenna facing away from the wireless fronthaul accesspoint and coupled to the RF filter for transmitting the radio signal,thereby providing access to user equipments (UEs) via the transmittedradio signal; wherein the wireless fronthaul access point therebywirelessly couples the remote baseband unit and the antenna-integratedradio.

The antenna-integrated radio provides a single channel of amulti-channel multiple input, multiple output (MIMO) antennaconfiguration. The antenna-integrated radio may be configured to provideLong Term Evolution (LTE) wireless access to UEs, and wherein thewireless fronthaul access point may further comprise an optical fiber orEthernet connection to the remote baseband unit. A second and a thirdantenna-integrated radio may also be provided for providing three sectorcoverage of an area, mounted on the radio mast in a triangularconfiguration with the antenna-integrated radio, each in communicationwith the wireless fronthaul access point for digital I and Q signalinginformation from the baseband unit. A second antenna-integrated radiomay also be provided, the antenna-integrated radio and the secondantenna-integrated radio further comprising a synchronization chip orusing global positioning system (GPS) hardware for synchronization. Thefirst and second millimeter wave wireless interfaces may 60 GHz WiGiginterfaces, and wherein the antenna-integrated radio may furthercomprise an additional Wi-Fi radio and an additional 60 GHz WiGiginterface. The antenna-integrated radio may be in communication withadjacent antenna-integrated radios mounted on the radio mast via a WiGigmesh network and may be configured for coordinated multiple-in,multiple-out (MIMO) operation with the adjacent antenna-integratedradios. The antenna-integrated radio may be configured to couple to azero-insertion force (ZIF) docking power socket as its only physicalconnection on the radio mast.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a first prior art radio architectureutilizing cabinet-based power amplification.

FIG. 2 is a schematic diagram of a second prior art radio architectureutilizing a remote radio head.

FIG. 3 is a schematic diagram of an antenna-integrated radio withwireless fronthaul capability, in accordance with some embodiments.

FIG. 4 is a schematic diagram of a radio architecture utilizing wirelessfronthaul, in accordance with some embodiments.

DETAILED DESCRIPTION

One way to understand the radio access network landscape is to separateit into its constituent parts. The radio access network involves abaseband processing chain for providing digital radio, a radio head thatinterfaces with the baseband and that includes antennas and poweramplifiers, and orchestration software. This application focuses onadvancing the state of the art in the radio head.

Currently, radio heads have various problems. One problem is that poweramplifiers are very inefficient. Power amplifiers (PAs) take an inputsignal and turn it into an output signal at a higher power. However,only roughly 10% to 40% of the power used by the PA is actually turnedinto radio transmission power. As PAs generate a lot of waste heat, thePAs additionally need cooling, which requires air conditioning, furtherconsuming the power budget. It is no wonder that some have said that thecellular radio access network consumes 0.5% of all global electricityconsumption.

Additionally, power is lost when a signal is transmitted over a cable.This is called cable loss. Each radio frequency (RF) cable used causessignal loss of 1-2 dBm, which can reduce the effective power of a 20W-rated antenna to 14 W. It follows that if 20 W is desired at theantenna, 30 W is needed at the radio head, which requires an additional100 W of power. Additionally, each RF connector also entails signalloss, called insertion loss, adding another 1 dBm of signal loss. Whenmultiple antennas per sector are considered, it is no wonder that agreat deal of power is expended simply for cooling the power amplifiers.

Another problem is fronthaul. Recently, the radio antenna functionalityand baseband processing functionality that used to be combined in a basestation have been separated, with a point-to-point fiber link betweenthe baseband and the antenna, making it easier to put the radiocomponents up on top of the cell tower and to service the basebandcomponents. This combination of radio components are called a remoteradio head, as the baseband is located elsewhere. However, the linkitself, which is called fronthaul, adds an additional complicationbecause currently only fiber is believed to have the performancecharacteristics needed to adequately service the radios. This is because100 Mbps of data capacity for a digital radio requires the equivalent ofmultiple gigabits per second to be transported by fronthaul to thebaseband for processing.

Although CPRI reduces cable loss to approximately 1.5 dBm by making thesignal digital, it does not solve the problem of cable loss entirely,because MIMO requires the two antennas to be physically separated.Handling the radio signal for two MIMO antennas at a single RRH requiressignals to be transported over an analog cable over at least somedistance to each MIMO antenna.

Another problem is that coming generations of the LTE standard areproposed that will increase the number of radios on the tower. Anincrease in the number of radios permits multi-band, multi-radio accesstechnology (multi-RAT) flexibility and performance, and providesopportunities to perform beamforming, coordinated multi-point (CoMP)inter-cell interference cancellation (ICIC), and other technologies.However, more radios mean more power, more baseband, and more fronthaul.

Another problem is electrical isolation. When lightning strikes a tower,it may cause electrical faults, as well as thermal ones. Unfortunately,since radio frequency cables are designed to be low impedance, so thatthey can transmit RF signals, the low impedance makes the equipment oneither side vulnerable to lightning strikes. Current base station towersare equipped with isolators between each RF component to preventlightning from causing cascading failures.

Another current area of inquiry is the appropriate and cost-effectiveidentification and location of filters. Filters are specific to aparticular frequency range, unlike wideband power amplifiers, which canhandle approximately 200 MHz of a frequency range efficiently. To avoidRF loss, ideally the filter and the power amplifier will be located inthe same enclosure. However, the enclosure must then handle the widerange of physical filter sizes needed to handle the differentfrequencies currently in use today.

Another current area of inquiry is thermal management. The powerexpended in the power amplifiers, baseband processors, and other aspectsof the radio frequency chain is output as heat, which reduces theoperational effectiveness of the system. Active heating, typically viaair conditioning, is one way to cool the system. Another way is passivecooling, typically via radiative cooling using a large thermal body andconvective air cooling. The level of heat being generated is reaching orexceeding the limits of what can be radiated using a thermal body ofreasonable size.

The combined problems of filter and thermal management contribute to theabsence of a standard, commodity radio head enclosure. Thermalengineering for a specific frequency and filter combination involvesdevelopment of custom cooling and enclosures for each frequency andfilter combination. Additionally, each enclosure requires carefulmachining of holes to avoid moisture ingress, and design to accommodateRF routing.

FIG. 1 depicts an example of a current-generation base station radioarchitecture with power amplification at the cabinet. In the figure, acabinet 118 includes a baseband unit, a power amplifier, and a filterfor each antenna and each frequency band on each antenna. The cabinet isalso inside a shelter 120, which also includes appropriately sized airconditioning 119 to cool the baseband in the cabinet. The airconditioning needs of this cabinet, which include power amplifiersconverting, for example, 40 watts per antenna into heat at 90%efficiency for a total of 400 W in heat generated from poweramplification, plus the digital processing baseband and other circuitry,are substantial.

RF wires 116 lead out of the cabinet 118 up mast 117 to the antennas.Mounted on the mast are twelve antennas 101, 102, 103, 104, 105, 106,107, 108, 109, 110, 111, and 112. Each of the antennas is fed by asingle RF wire 113, which is part of the bundle of wires 116 thatconnects back to the cabinet. However, as the RF cables have at least1.5 to 2 dBm signal loss on their way up the mast, a tower-mountedamplifier is required to re-amplify the signal before it is fed to eachantenna. As shown, tower-mounted amplifier 115 receives the signal wire116, amplifies the signal, and outputs it to antenna 114 via signal wire113. The antenna configuration shown is a three-sector configurationwith each sector equipped with 4×4 multiple-in, multiple-out (MIMO)capability. Each antenna has a tower-mounted amplifier. A duplexer maybe present within the antennas to enable receive and transmit to bemultiplexed over the same cable. The 1.5 to 2 dBm loss is the equivalentof turning 30 W of RF at the cabinet into 20 W at the antenna.

FIG. 2 depicts another example of a current-generation base stationradio architecture, using remote radio head architecture. In the figure,a cabinet 219 includes a baseband unit. The cabinet is also inside ashelter 221, which also includes appropriately sized air conditioning220 to cool the baseband in the cabinet, which requires less airconditioning than cabinet 118 but still requires substantial airconditioning. The baseband in the cabinet has a fiber optic outputconnection 217 using the common public radio interface (CPRI) protocoland small form factor pluggable (SFP) connectors to fiber The basebandalso has a power output 216 to deliver power for the remote radio head.CPRI fiber extends up the pole or mast 218 to the radio head 205(although the point of connection is not shown), which is on the towerbut not at the antenna. The radio head 205 has an CPRI interface to thebaseband unit, and has RF cable connections to each of the twelveantennas 201, 202, 203, 204, 206, 207, 209, 210, 211, 212, 213, 215. Theantennas are arranged in the figure as four antennas for each of threesectors. The radio head takes the output of the CPRI interface, which isdigital, turns it into an analog radio frequency signal, amplifies itthrough a PA, and performs filtering through a filter, before sending itthrough radio frequency cables to each antenna; all the RF cables exitas shown at cable bundle 208, and connect to the antennas; for example,RF cable 214 connects RRH 205 to antenna 215. Less air conditioning isneeded, as the radio head is air cooled. However, the radio frequencycables have significant RF signal loss of at least 0.5 dB.

A new approach is suggested to ameliorate these problems. Greaterflexibility, as well as reduced signal loss and consequently reducedpower consumption, are made possible using the disclosed approach. Oneor more of the following components may be combined to create animproved base station.

Firstly, a wireless fronthaul access point is proposed. A multi-sectorbase station tower is typically configured with radio heads mounted in atriangular configuration. By placing a wireless fronthaul access pointin the center of the triangle, the base station can be located veryclose to the RRHs, i.e., within line of sight or in some cases withinapproximately 5 meters. This proximity allows the use of high-bandwidthradio technologies, such as Wi-Gig, to provide multi-gigabit (5-10 Gbps)bandwidth to each radio head, to take the place of CPRI and providefronthaul for all I and Q signals going into and coming out of theantennas.

Second, each radio head is configured to include an antenna, SDR,filter, and PA or LNA for a single channel of a multi-channel MIMOconfiguration. Using the example of a 2×2 MIMO installation, each radiohead provides a “half-RRH” or “single-channel RRH,” with its outputremotely controlled by the baseband unit.

Third, MIMO installations have not previously split signals from asingle MIMO configuration across devices. The reason is that processingof antenna signals needs to be performed together. Greater coordinationand synchronization among the baseband units enables this. Specifically,higher degrees of synchronization, up to and including 1 part perbillion of synchronization, are combined with rapid processing andhigh-bandwidth wireless links to enable separate, coordinated processingof the individual RRH signals.

Fourth, the use of wireless fronthaul ensures that each antenna requiresonly power to be physically connected. A physical docking system isdescribed that provides power and additional features, such asorientation configurability, while only requiring an antenna system tobe dropped in with a small degree of force to connect to power.

A configurable, rapidly-deployable, high-performance base station isthereby enabled by the combination of one or more of these components.

Small cell systems on a chip (SOCs) may be used to drive a small formfactor baseband board colocated with an antenna. The baseband board mayhave the processing power to provide wireless access to users on awireless access network. Multiple such baseband-integrated antennas maybe combined to provide multi-sector wireless access service.

Wireless radios may be integrated into the antennas for short-distanceinter-antenna communication. The radios may operate at a high frequency,such as millimeter-wave or 60 GHz, and may be WiGig, 802.11ad, or otherwireless radios; these radios will be referred to as WiGig radios inthis disclosure. At high frequencies such as used by these radios, highdata rates are possible, sufficient to handle the digital data demandsfor digital fronthaul traffic, with minimal interference to thereception and transmission frequencies of the radios. The wireless rangelimitations of frequency bands in the tens of gigahertz (i.e., microwaveor millimeter wave) are not problematic, as the antennas areco-located/mounted on the same radio tower. Moreover, the WiGig radioscan replace two RF cables and 4 connectors, significantly mitigatingpower loss. The antennas may thus be feederless, using wireless for the“last inch” of fronthaul.

The bandwidth required for a wireless fronthaul interface depends on thebackhaul bandwidth needed for connected user devices. A typical LTEfrequency band requires either 10 or 20 MHz of bandwidth. Whenmultiple-in, multiple-out (MIMO) technologies are used, the bandwidthrequired for 10 MHz ranges from 1.2 Gbps for 10 MHz, 2×2 MIMO to 9.8Gbps for 20 MHz, 8×2, 8×4, 8×8 MIMO. WiGig currently supports 7 Gbps,enabling fronthaul for all but the 20 MHz 8×8 MIMO case, and futurewireless technologies using higher-rate radios may also be incorporatedto support such cases. The fronthaul connection may also accommodateMIMO, ICIC, DPD, and other digital processing scenarios. The fronthaulconnection may also accommodate compression of the raw digital signal,in some scenarios, such as lossless I/Q compression or frequency domaincompression.

Unlike with other remote radio head solutions, in some embodiments, anentire baseband board may be placed inside each antenna. In the case ofa MIMO antenna, which is configured to be used as one of multipleantennas, the baseband board may be enabled to handle the input andoutput streams for that specific antenna. One power amplifier may belocated in each antenna as well. The WiGig radio may be used asfronthaul, replacing a fiber connection. Heat dissipation may beimproved by leveraging of the antenna thermal mass. Low-bandwidthdigital signals are input into the antenna, high-bandwidth digitalfronthaul is avoided or is transmitted over high-bandwidth digitalwireless signals, and RF signal loss is reduced, along with powerconsumption. The combined unit is able to be manufactured at scale forsignificantly reduced cost.

In some embodiments, instead of using a single fronthaul WiGig accesspoint for the central WiGig controller, one wireless fronthaulintegrated antenna may act as a master, and other integrated antennasmay act as slaves. In some embodiments, a resilient master-slavearchitecture may be used such that another antenna may automaticallyprovide failover for a base station. In some embodiments, one masterantenna may have multiple slaves.

In some embodiments, backhaul may also be wireless. A lower-bandwidthwireless interface may be used, including another WiGig interface or aWi-Fi interface. Backhaul to one antenna may be shared with otherantennas, in a mesh network.

In some embodiments, when the only required physical interface is power,installation and maintenance are significantly improved. Current methodsfor troubleshooting errors when a remote data connection is unavailableentail a technician climbing the tower to reach the errant antenna. Whenthe antenna is significantly less expensive, the entire antenna modulemay simply be replaced. In some embodiments, a replacement antenna maybe installed via drone, or using a less-expensive technician to connectpower.

As the physical enclosure requires only power and/or a wired Ethernetport, the RF connector machining requirements may be relaxed, and thecost of the enclosure itself may be reduced. The enclosure may be asimple block of cast metal, large enough for a single filter appropriatefor any frequency band. Minimal holes may be machined. Aradio-transparent section may provide egress for radio frequencysignals. The radio-transparent section may be configured on the tops andthe bottoms of the enclosure, such that the antennas provide visibilityto all other antenna modules on the tower, as well as the wirelessbackhaul connection antenna. Although WiGig signals do not penetrate iceand snow, the thermal dissipation from the antenna module, particularlyin the transparent region, is anticipated to result in melting of suchsnow or ice.

In some embodiments, filters may include, for example, cavity filters,or ceramic filters. Filters may be made of cast aluminum (in particularfor cavity filters), or from ceramic. Filters may be combined formultiple bands of operation. Filters may be of varying sizes forhandling radio bands with different wavelengths.

In some embodiments, reducing dB loss by 0.5 can result in a 10%reduction in power amplifier power output, which can save 10% of theenergy consumption budget of the PA. This power savings can be canceledout by the power consumption of the baseband unit. However, as the poweris consumed at both the baseband board and the power amplifier, coolingrequirements are still improved over the use of a highly power-consumingpower amplifier. Another difference in heat generation is that the poweramplifiers, which used to be centralized across multiple antennas withina single baseband unit, are not spread out over multiple antennas. Thisalso improves cooling requirements. Total reduction of thermal mass is10-20%.

An additional benefit of locating the power amplifier in the antenna isincreased power amplifier resiliency. Even if one power amplifier fails,its failure is contained to the particular antenna it is located in.This is in contrast to traditional installations, where power amplifierfailures can cascade. Power amplifiers typically fail due tooverheating. When they are contained together within a single cabinet,more than one of them may fail at once due to heat-related issues orlightning. This likelihood is reduced when the PAs are physicallyseparated.

Another benefit is electrical isolation. Using wireless fronthaulremoves the need to connect antennas and other components usinglow-impedance RF cable, thereby providing near-complete electricalisolation. This has a side benefit of reducing complexity by eliminatingthe need for electrical isolators between each component, and thisreduction in complexity allows operators to more easily troubleshoot andmaintain the equipment.

Without tower amplification and RF loss, sensitivity is improved on thereceive side. No significant cabinet being needed, rooftop installationis simplified. Multiple bands may be enabled using multiple antennamodules, each mounted to a single antenna or single tower. The towerneed only provide adequate space for RF filters of the appropriatefrequency band.

FIG. 3 shows the components that would be used in such a device.Integrated antenna radio head 300 includes the following components. Aprocessor 302 is connected to a processor memory 303, which may be usedtogether to perform operations described herein. Processor 302 isconnected to a first WiGig radio 310, which is connected to a fronthaulAP (not shown) via WiGig at a high data rate, and to the processor 302.Processor 302 is also connected to a second WiGig radio 311, which isconnected to another radio head via another WiGig connection. Processor302 is also connected to a backhaul connection 312, which may be a802.11n/ac connection or an Ethernet connection. The WiGig radiosprovide their own on-chip antennas, in some embodiments. Processor 302may provide routing or switching between interfaces 310, 311, and 312and may receive digital I and Q data from the backhaul connection or theWiGig fronthaul and may send the digital I/Q to the baseband processor.A baseband processor 306 may be connected to the processor 302 and to abaseband memory 308. The baseband processor 306 is connected to thecellular transmit/receive (TRX) chain 314 of the antenna radio head,which includes power amplifier 314 a and RF filter 314 b fortransmission, as well as other RF functions, such as a duplexer forprocessing received RF signals. The cellular TRX chain receives analogRF I and Q from the baseband processor 306 and outputs it to the accessantenna (not shown).

An IEEE 802.11n Wi-Fi radio may be used to provide additional backhaulsupport, with or without Ethernet backhaul. A baseband board may beprovided to perform all baseband functions specific to this antenna. Thebaseband board may include DPD and CFR functions, as well as self-testroutines and modules, as well as handling for one or more channels ofMIMO, or one or more channels of multiple radio access technologies,e.g., 2G, 3G, 4G, UMTS, LTE, and the like. A system-on-chip may be usedfor any combination of these components. The enclosure may include twoWiGig radios. One of the WiGig radios may connect to a wirelessfronthaul access point (AP) located at the center of the mast. As theWiGig antennas have limited range, it is useful that the fronthaul AP islocated within line of sight and within a short distance away, for allantennas on the mast. In some embodiments, one WiGig radio may connectto another antenna on the base station; in other embodiments, anadditional WiGig antenna may be provided for redundancy. The enclosuremay also include a power amplifier and a filter, and the physicalantenna component. The power amplifier could be a 30 W power amplifier,in some embodiments. The enclosure needs only to have power, andoptionally wired Ethernet. With a traditional enclosure, the holesrequire careful drilling that is different for each application. Here,as the enclosure thus has fewer holes, it is more reproducible and lessexpensive to produce, as well as having fewer holes for water ingress.

FIG. 4 shows a system including the embodiment of FIG. 3. At the top ofmast 419, wireless fronthaul access point 405 is provided at the top ofa mast 419 and fed by one wires, fiber 420 for backhaul and power (notshown). Power 418 is also carried up the mast by a cable 418 and isdistributed by a power distribution system built into the mast andconnected to each antenna; ordinary 48 V DC power may also be providedto each of the antennas. Antennas 401, 403, 404, 406, 408, 409, 410,411, 412, 413, 414, 415 are fed digital I and Q signals wirelessly bythe fronthaul AP 405, which wireless signal is shown as 402; they pointoutward to provide access and they each have WiGig antennas pointedtoward the fronthaul AP. The rear of antenna 406 shows exemplary heatdissipation fins 407, which, together with the thermal mass of theantennas, is enough to dissipate heat passively. Antennas 414 and 415communicate in a WiGig daisy chain with antennas 415 and 417respectively, as shown by wireless signals 416 and 417.

WiGig is used between each of the four antennas to provide fronthaul.Wi-Fi (802.11ac, in the 5 GHz band) is used for backhaul from each ofthe antennas. The only physical connection at the antenna may be power,in some embodiments, or Ethernet and power. No RF cable loss isentailed. No tower amplifier, combiner or splitter is required on oraround the tower.

At the bottom of the mast, cabinet 421 no longer needs a shelter withair conditioning, as the reduction in power wastage and increase inthermal mass enables passive cooling at the cabinet. Therefore, no ACand no baseband unit are found at the cabinet; instead, only a passivelycooled power supply and a backhaul network terminal are provided in thecabinet.

In some embodiments, a power tilt antenna chassis may be provided. Insome embodiments, a winch that can lower itself and that causes theantenna to guide itself into position when it is raised can be deployedat the tower in a base or cradle for the antenna module. A drone mayoperate an electric latch to release an antenna module, and the antennamodule may lower itself to the ground using the winch. In someembodiments, a boom and trolley may be attached at the center of a towerfor attaching and detaching antenna modules. The antenna chassis and/orbase may be physically designed to be self-guiding, such that a newantenna may be inserted into the base by a drone or by an operator.

In some embodiments, wireless synchronization may be used betweenantennas. Synchronization is important for various applications, such astime division duplexing (TDD) for certain cellular bands. Directwireless synchronization could be provided, for example using a methodsuch as described as in U.S. Pat. No. 9,048,979. Alternatively, eachantenna subsystem may be equipped with its own GPS antenna, and the GPSantennas may be used to sync the antennas together down to approximately50 parts per billion (ppb).

In some embodiments the industrial, scientific and medical (ISM)unlicensed radio band may be used, for wireless sync, wirelessfronthaul, wireless backhaul, mesh networking, daisy-chaining, oranother purpose. In some embodiments a high-bandwidth high-frequencyband, such as 60+ GHz, could be used.

In some embodiments, different electrical energy transfer methods may beused. For example, a packet energy transfer protocol, such asVoltServer, or Power over Ethernet, may be used to distribute power overa wired Ethernet port to each antenna module, with no electrician neededfor installation. VoltServer provides a certain amount of energy inshort time slices that are akin to digital packets. VoltServer alsocarries data as well as energy in each packet. Using the data,VoltServer also monitors the impedance on the circuit so that power canbe cut rapidly with any change in impedance. As the individual energypulses do not contain a hazardous level of energy, VoltServer providesan alternative to high-voltage wires that pose danger to people. Anenergy transfer system may use high-impedance cables, such as theEthernet cables used by VoltServer. These high-impedance cables provideelectrical isolation and thereby reduce the risk of electrical failure.The data connection provided by VoltServer may be used instead of or inconjunction with wireless fronthaul, in some embodiments.

In some embodiments, the baseband boards integrated into the antennasmay have sufficient processing power to perform digital pre-distortion(DPD) and/or crest factor reduction (CFR).

In some embodiments, alternative fronthaul may be employed inconjunction with, or in place of, the WiGig interfaces described above.In some embodiments, a small form factor-pluggable (SFP) patch cablefronthaul may be used, either in conjunction with or in place of theWiGig wireless fronthaul connection. An appropriate number of SFPconnections may be used, if substituting for the WiGig fronthaul. Patchcables may be used without the use of SFP connectors. Fiber may be usedfor fronthaul between the antennas. Fiber may be laid as a backup to adedicated baseband cabinet, using, for example, the CPRI protocol, and asoftware decision may be made whether to use the L2/L3 interface at thebaseband cabinet or at the antennas. Enhancements for CoMP may beprovided such that antenna modules may provide CoMP, or CoMP may beprovided based on the level of fronthaul capacity available, e.g., if ahigher-bandwidth CPRI fiber fronthaul connection is available, or ifhigher-bandwidth wireless fronthaul is available, a gradient of CoMPenhancements may be made available.

In some embodiments, the antenna components may be deliverable by droneand may use a zero-insertion force (ZIF) connector.

In some embodiments, the dock may include antenna tilt control. In someembodiments, the tilt control may involve a wired or wireless connector.

In some embodiments, the antenna may support a physically-wiredconnection.

In some embodiments, the antennas can wirelessly daisy-chain with eachother, enabling increased resiliency and robustness. In someembodiments, the antennas can form a mesh network.

In some embodiments, the antennas may be configured with a Wi-Gigantenna module on the back of the cellular band antenna, such that thewireless fronthaul access point is located in a non-obstructed locationfor all antennas. The Wi-Gig antenna module or other gigabit wirelessmodule may be part of the antenna on a chip in a baseband board, and maybe covered by a radio-transparent radome or shield, made, for example,out of plastic. Where a heat-dissipating enclosure is used, the Wi-Gigantenna or gigabit wireless module may be physically located on theexterior of the enclosure, in some embodiments. In some embodiments,where the Wi-Gig or gigabit wireless module is located on the exteriorof the enclosure and not on a baseband card, the Wi-Gig or gigabitwireless module may be physically coupled to the baseband card via astandard serial digital interface.

In some embodiments, two or more wireless fronthaul access points may beprovided for additional resiliency, each located in the same locationwithin the triangle of the tower mount.

In some embodiments, a single wireless access point may be used, and maybe located, for example, in the middle of the tower between all theantennas, with each antenna receiving wireless fronthaul or wirelessbackhaul, or both. This may enable reduction of cost of providing allthe processing power to each antenna. In some embodiments a singleantenna may bear the bulk of the processing burden, and may bedaisy-chained to the other antennas.

In some embodiments, the wireless fronthaul access point may have anomnidirectional antenna, or a directional antenna.

In some embodiments, multiple bands, or wireless frequencies, may besupported by each antenna and/or by the wireless fronthaul access point.

In some embodiments, the wireless fronthaul link may be a Wi-Gig link ora Li-Fi link or another type of high-bandwidth wireless link. In someembodiments, the wireless link may carry an I signal, a Q signal, andmanagement data. Multiple bands of I and Q signals may be carried.Management data may include alarms, notifications, tilt management, andother features. In some embodiments, sync data may be carried. In otherembodiments, sync data may be achieved using analysis of the wirelesssignals already being transmitted, such as described in U.S. Pat. No.9,048,979, hereby incorporated herein in its entirety.

In some embodiments, alternative thermal management solutions may beprovided. For example, surface mount piezoelectric cooling jettechnology, such as is provided by General Electric, may be applied toincrease cooling capacity without the use of air conditioning.

Although the methods above are described as separate embodiments, one ofskill in the art would understand that it would be possible anddesirable to combine several of the above methods into a singleembodiment, or to combine disparate methods into a single embodiment.For example, all of the above methods could be combined. In thescenarios where multiple embodiments are described, the methods could becombined in sequential order, in various orders as necessary.

Although the above systems and methods are described in reference tobase stations for the Long Term Evolution (LTE) standard, one of skillin the art would understand that these systems and methods could beadapted for use with other wireless standards or versions thereof.

Although the present disclosure has been described and illustrated inthe foregoing example embodiments, it is understood that the presentdisclosure has been made only by way of example, and that numerouschanges in the details of implementation of the disclosure may be madewithout departing from the spirit and scope of the disclosure.

The invention claimed is:
 1. A system, comprising: a wireless fronthaulaccess point coupled to a radio mast and in communication with a remotebaseband unit, the wireless fronthaul access point further comprising afirst millimeter wave wireless interface; and an antenna-integratedradio for providing access to user equipments (UEs), mounted within lineof sight on the radio mast with the wireless fronthaul access point, theantenna-integrated radio further comprising: a second millimeter wavewireless interface configured to receive digital I and Q signalinginformation from the remote baseband unit wirelessly via the wirelessfronthaul access point, a radio transceiver configured to receive thedigital I and Q signaling information and output an access radio signal,a power amplifier coupled to the radio transceiver and configured toamplify the access radio signal from the radio transceiver, the poweramplifier contained within an enclosure of the antenna-integrated radio,a radio frequency (RF) filter coupled to the power amplifier andconfigured to filter the access radio signal from the power amplifier,and an antenna coupled to the RF filter for transmitting the accessradio signal, thereby providing access to user equipments (UEs) via thetransmitted access radio signal; wherein the wireless fronthaul accesspoint thereby wirelessly couples the remote baseband unit and theantenna-integrated radio.
 2. The system of claim 1, wherein theantenna-integrated radio provides at least one channel of amulti-channel multiple input, multiple output (MIMO) antennaconfiguration.
 3. The system of claim 1, wherein the antenna-integratedradio is configured to provide Long Term Evolution (LTE) wireless accessto UEs.
 4. The system of claim 1, further comprising a remote basebandunit in communication with the wireless fronthaul access pointconfigured to perform processing of the digital I and Q signalinginformation and to send the processed digital I and Q signalinginformation to the wireless fronthaul access point.
 5. The system ofclaim 1, wherein the wireless fronthaul access point further comprisesan optical fiber or Ethernet connection to the remote baseband unit. 6.The system of claim 1, further comprising a second and a thirdantenna-integrated radio for providing three sector coverage of an area,mounted on the radio mast in a triangular configuration with theantenna-integrated radio, each in communication with the wirelessfronthaul access point for digital I and Q signaling information fromthe baseband unit.
 7. The system of claim 1, further comprising a secondantenna-integrated radio, the antenna-integrated radio and the secondantenna-integrated radio further comprising a synchronization chip orusing global positioning system (GPS) hardware for synchronization. 8.The system of claim 1, wherein the antenna-integrated radio and thewireless fronthaul access point each further comprise a synchronizationchip or global positioning system (GPS) hardware for synchronization. 9.The system of claim 1, wherein the first and second millimeter wavewireless interfaces are 60 GHz interfaces, and wherein theantenna-integrated radio further comprises an additional 2.4 GHz radioand an additional 60 GHz interface.
 10. The system of claim 1, whereinthe antenna-integrated radio is in communication with adjacentantenna-integrated radios mounted on the radio mast via a WiGig meshnetwork and is configured for coordinated multiple-in, multiple-out(MIMO) operation with the adjacent antenna-integrated radios.
 11. Thesystem of claim 1, wherein the antenna-integrated radio is configured tobe installed via a zero-insertion force (ZIF) docking power socket by adrone.
 12. The system of claim 1, further comprising a plurality ofadditional antenna-integrated radios configured to communicate with thewireless fronthaul access point in a daisy chain topology via theantenna-integrated radio.
 13. The system of claim 1, further comprisinga plurality of additional antenna-integrated radios configured as slaveantennas of the antenna-integrated radio.
 14. The system of claim 1,further comprising a plurality of additional antenna-integrated radiosconfigured to communicate with each other and with the wirelessfronthaul access point in a mesh network.
 15. The system of claim 1,wherein the wireless fronthaul access point is configured to accommodatemultiple-in, multiple-out (MIMO), inter-cell interference cancellation(ICIC), crest factor reduction (CFR), or digital pre-distortion (DPD)processing of the digital I and Q signaling information.
 16. The systemof claim 1, wherein the wireless fronthaul access point is configured toprovide a fronthaul access point for multiple-in, multiple-out (MIMO)signals, and further comprising a plurality of additionalantenna-integrated radios synchronized with the wireless fronthaulaccess point to enable coordinated processing of individual MIMOsignals.
 17. A method, comprising: at an antenna-integrated radio:receiving, at a millimeter wave wireless interface, a digital I and Qsignaling information from a remote baseband unit wirelessly via awireless fronthaul access point; receiving, at a radio transceiver, thedigital I and Q signaling information to output an access radio signal;amplifying, at a power amplifier coupled to the radio transceiverinternally within the antenna-integrated radio, the access radio signalfrom the radio transceiver; filtering, at a radio frequency (RF) filtercoupled to the power amplifier internally within the antenna-integratedradio, the access radio signal from the power amplifier; andtransmitting, at an antenna coupled to the RF filter internally withinthe antenna-integrated radio, the access radio signal, thereby providingaccess to user equipments (UEs) via the transmitted radio access radiosignal.